Any other alternative routes or suggestions would be greatly appreciated  Thank you 

Alternative investments have become more readily available, accepted and even desired.

Alternatively, do you think the best option is to just wait until he is ready to sell them, and purchase each of them one at a time over the next couple of years? 

Alternatively, you could get a Heloc from Pen Fed. 

I would recommend having a talk with your cousin and finding out what exactly they are looking for return wise - that way you can almost work backwards to find an arrangement/split that works, or in the alternative, discover that no real split is even possible given revenue (or lack there of) generated by the property.Best of luck 

In our market we haven’t been asked to consider other alternatives. 

Alternatively, you could also work with a HML, they are more expensive but do give you an extra set of experienced eyes looking at the project and someone controlling the draws to ensure work is done before a contractor is paid.

I have found an article that explains opportunity zones, if this helps. https://www.wealthmanagement.com/alternative-investments/opportunity-zones-explained

Are there alternatives to yellow letters?

The wholetail alternative has several possibilities that could bottleneck your earnings.